n1sdp/n1sdp_smt: add module n1sdp_smt

This patch adds n1sdp_smt module taken from core smt module but
modified to support smt master interface APIs. This modification
resides under product folder until SCMI agent support is added in
core module.

Change-Id: I42dc986b6cb8a430081ec69eb698ac61618d4791
Signed-off-by: Manoj Kumar <manoj.kumar3@arm.com>